Hibernate DetachedCriteria 查询set 类型的字段
Hibernate DetachedCriteria 查询set 类型的字段
例：
publicclassUsers{
privateSetchallenges=newHashSet(0);
}
publicclassChallenge{
privateIntegerchallengeid;
privateUsersusers;
}
User和Challenge是一对多的关系
现在想根据Users中的challenges.challengeid的某一个属性查询
challenges是一个属性
<script type="text/javascript"></script>DetachedCriteria detachedCriteria=DetachedCriteria.forClass("Users");
detachedCriteria.createAlias("challenges","c").add(Restrictions.eq("c.challengeid","查询值"));
Java代码
DetachedCriteria detachedCriteria=DetachedCriteria.forClass("Users");
detachedCriteria.createAlias("challenges","c").add(Restrictions.eq("c.challengeid", "查询值")); DetachedCriteria detachedCriteria=DetachedCriteria.forClass("Users");
detachedCriteria.createAlias("challenges","c").add(Restrictions.eq("c.challengeid", "查询值"));我查询的网页:
http://topic.csdn.net/u/20090616/10/3e8d5f18-7144-4248-85a4-41bf5c4e3903.html
http://stackoverflow.com/questions/1987471/nhibernate-exclude-a-property-from-a-projection-list-select-clause
http://topic.csdn.net/u/20080225/13/9eb2fbf7-117b-41f4-84d6-4b5461780388.html
希望能帮助你1、Users实体
public class Users implements java.io.Serializable {
// Fields
private Long id;
private String userName;
private Set challenges = new HashSet(0);
......
} public class Users implements java.io.Serializable {
// Fields
private Long id;
private String userName;
private Set challenges = new HashSet(0);
......
}表记录：
iduser_name
1小明
2小强
2、Challenge实体
public class Challenge implements java.io.Serializable {
// Fields
private Long challengeid;
private Users users;
private String challengeName;
......
} public class Challenge implements java.io.Serializable {
// Fields
private Long challengeid;
private Users users;
private String challengeName;
......
}表记录：
idchallenge_nameuser_id
1挑战11
2挑战21
3挑战32
3、根据challengeid查询Challenge对象，再关联出相应的users信息
// 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Challenge.class);
detachedCriteria.add(Restrictions.eq("challengeid", new Long(1)));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Challenge challenge = (Challenge) resultList.get(i);
// 打印出challenge所关联的users信息
System.out.println(challenge.getUsers().getUserName());
}
} // 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Challenge.class);
detachedCriteria.add(Restrictions.eq("challengeid", new Long(1)));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Challenge challenge = (Challenge) resultList.get(i);
// 打印出challenge所关联的users信息
System.out.println(challenge.getUsers().getUserName());
}
}结果输出：
小明
4、根据challengeName模糊查询查询Challenge对象，再关联出相应的users信息
// 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Challenge.class);
detachedCriteria.add(Restrictions.like("challengeName", "%" + "挑战" + "%"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Challenge challenge = (Challenge) resultList.get(i);
// 打印出challenge所关联的users信息
System.out.println(challenge.getUsers().getUserName());
}
} // 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Challenge.class);
detachedCriteria.add(Restrictions.like("challengeName", "%" + "挑战" + "%"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Challenge challenge = (Challenge) resultList.get(i);
// 打印出challenge所关联的users信息
System.out.println(challenge.getUsers().getUserName());
}
}结果输出：
小明
小明
小强
5、根据users查询，查询小明对应的所有Challenge信息
// 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Users.class);
detachedCriteria.add(Restrictions.eq("userName", "小明"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
Set set = ((Users) resultList.get(0)).getChallenges();
// 循环打印出小明对应的所有Challenge信息
for (Iterator it = set.iterator(); it.hasNext();) {
Challenge challenge = (Challenge) it.next();
System.out.println(challenge.getChallengeName());
}
} // 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Users.class);
detachedCriteria.add(Restrictions.eq("userName", "小明"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
Set set = ((Users) resultList.get(0)).getChallenges();
// 循环打印出小明对应的所有Challenge信息
for (Iterator it = set.iterator(); it.hasNext();) {
Challenge challenge = (Challenge) it.next();
System.out.println(challenge.getChallengeName());
}
}结果输出：
挑战2
挑战1
// 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Users.class);
detachedCriteria.createAlias("challenges", "cs");
detachedCriteria.add(Restrictions.like("cs.challengeName", "%" + "挑战" + "%"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Users user = (Users) resultList.get(i);
System.out.println(user.getUserName());
}
} // 查询条件
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Users.class);
detachedCriteria.createAlias("challenges", "cs");
detachedCriteria.add(Restrictions.like("cs.challengeName", "%" + "挑战" + "%"));
Criteria criteria = detachedCriteria.getExecutableCriteria(session);
// 查询
List resultList = criteria.list();
if (resultList != null && resultList.size() > 0) {
for (int i = 0; i < resultList.size(); i++) {
Users user = (Users) resultList.get(i);
System.out.println(user.getUserName());
}
}输出结果：
小明
小明
小强
重复结果可以再过滤，这个应该是你想要的查询方式
7、为了避免resultList中的重复记录, 可以转换为Set集合, Set中存放的记录不允许相同。
以下是对第6的结果进行去重复记录
Java代码
Set resultSet = new HashSet();
// 添加以后自动去掉重复记录
resultSet.addAll(resultList);
// 循环打印出小明对应的所有Challenge信息
for (Iterator it = resultSet.iterator(); it.hasNext();) {
Users user = (Users) it.next();
System.out.println(user.getUserName());
}
<hibernate-mapping>
<class table="table1">
<set name="table2" table="table2" lazy="true" cascade="all">
<key column="result_id"/>
<many-to-many column="group_id"/>
</set>
</class>
</hibernate-mapping>
select t2.property1, t2.property2, ...
from table1 as t1
inner join t1.table2 as t2
select t1.table2.property1, t1.table2.property2, ... from table1 as t1